SAN DIEGO — Africanized "killer" bees are expected to reach California within a few years and San Diego County agriculture officials are preparing for their arrival.

The county agricultural commissioner's office has set a bee trap near each of the county's three border crossings--San Ysidro, Otay Mesa and Tecate. And state agriculture officials have set three traps of their own in the county, including one at the Port of San Diego, where they fear the bees are most likely to enter.

Although their venom is no more potent than that of the native European variety found in the United States, the Africanized insects sting in larger swarms and generally pursue an intruder for a longer time over a greater distance.

More than 300 people reportedly have died in the course of the Africanized bees' northward movement since they were released from a laboratory in Brazil in 1956. The unpredictable bees are a cross between European bees and an African strain.

In addition to posing a public health problem, the Africanized bees would threaten crops in California that rely on pollination, an industry worth $2 billion a year, and to the state's $18-million-a-year honey production business, said David Kellum, an entomologist with the San Diego County agricultural commissioner's office.

"We are on the front line as one of the first counties in California that will be hit by the Africanized bee," Kellum said. "If we have a stinging incident here, it will become national news. The county will have to coordinate its efforts with the tourist industry to assure the people the situation is under control."

Baited with a pheromone that attracts bees, the county's traps are made of corrugated paper and designed to look like a hollow tree. Biologists check the traps once a week, when the bees are killed with a spray and taken to a laboratory where scientists determine if any of them are Africanized bees.

State officials have set about 36 traps throughout California, primarily in coastal areas where the bees might come ashore on ships.

Scientists expect the Africanized bees to arrive in Texas early next year and in San Diego two to five years later. They are now found as far north as the Mexican state of Veracruz, about 300 miles south of Brownsville, Tex. Officials believe the bees are more likely to enter along coastal areas such as San Diego rather than in areas such as the Imperial Valley, because the Africanized bees have an aversion to deserts.

State agricultural officials won the first round with Africanized bees. In June, 1985, a colony was discovered in an oil field about 45 miles northwest of Bakersfield. Bee experts theorized the the colony had arrived hidden in a load of oil-drilling pipe shipped from South America.

After inspecting 22,000 apiaries in Kern County, state officials destroyed 12 colonies containing Africanized bees and lifted a quarantine on 1,088 square miles of the southern San Joaquin Valley.

As the largest bee-keeping state in the nation, California will be particularly hard hit by the Africanized bees, said Pat Paswater, apiary projects leader with the state Department of Food and Agriculture.

Professional pollinators who transport bees to farms and fields face the problem of attempting to control the Africanized bees. Fields might have to be abandoned by human workers while the bees pollinate crops. For those in the honey business, the Africanized bee presents another problem besides its ill temper: It devours much of its own honey, making it a less-efficient honey producer than the European bee.

When the Africanized bees come in contact with the European strain, the African traits are dominant: a European strain of bee becomes Africanized when it crossbreeds with bees carrying genes from the African bees. Rather than coexist with other bees, Africanized bees take over hives, push aside rivals and dominate mating.